More than 500 people between the ages of 15 and 59 took part in last year's event, including swimmers from France and Finland.

Leningrad region authorities have banned a yearly race in which participants compete to see who can swim the fastest riding an inflatable sex doll.

The yearly competition, into its 10th year and known as the Bubble Baba Challenge, was set to take place Aug. 25 in the Leningrad region's Priozersky district.

But this year, authorities refused to grant permission for the lighthearted event, telling organizers that the water level in the Vuoksa River is dangerously high and that road and rail bridges are being repaired downstream, state-run NTV television reported.

Organizers say the ban is unfair, suspecting that authorities only refused permission because of wider efforts to clamp down on mass gatherings after protests against President Vladimir Putin's rule.

Event organizers told NTV that they had taken various safety precautions to cope with this year's increased water flow, including only allowing those 16 and older to take part and working out a safe route in advance.

The Bubble Baba Challenge 2012 was set to take place under the slogan: "A rubber woman isn't anything more than a means of transportation."

At last year's event, 543 people between the ages of 15 and 59 years old took part, including swimmers from France and Finland, according to the Bubble Baba Challenge website.